To choose a skin for your site, go to 'Regional Setup
> Lang & Email Setup' and choose which language
you want to set the skin for. In the form that opens, you can the skin
from the 'theme' menu. If there are multiple masterpages in the skin,
you can choose one of those too.
If you leave either selection blank, Kartris will use the defaults (which are the skin 'Kartris' and the 'Template.master' template file).
This menu automatically picks up any new folders added to the /Skins folder within a Kartris site. So all you have to do to import or create a new skin is to place the new folder there and then select it from this menu.
Rather than modify the default Kartris skin, we suggest you clone it, and then select your new skin's name and develop from there.